Wikipedia gives the altitude of Amsterdam as "−2 m". I'm not sure what that means, exactly. Is it a typical road surface that's at two metres below mean sea lev

Wikipedia gives the altitude of Amsterdam as "−2 m". I'm not sure what that means, exactly. Is it a typical road surface that's at two metres below mean sea level? Can anyone explain where mean sea level is in a typical Amsterdam street scene like this one (https://commons.wikimedia.org/wiki/File:Red-light_district_of_Amsterdam_by_day._2012.JPG https://commons.wikimedia.org/wiki/File:Red-light_district_o...)?